基于相位梯度光栅介电超表面的高效太赫兹波异常反射器  

High-efficiency terahertz wave anomalous reflector based on dielectric metasurface of phase gradient grating

作　　者：苏英蔚 田震[1] Su Yingwei;Tian Zhen(Center for Terahertz Waves and School of Precision Instrument and Optoelectronics Engineering,Key Laboratory of Optoelectronic Information Technology(Ministry of Education of China),Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学、精密仪器与光电子工程学院太赫兹研究中心、光电信息技术教育部重点实验室,天津300072

出　　处：《红外与激光工程》2023年第2期312-318,共7页Infrared and Laser Engineering

基　　金：国家重点研发计划(2017YFA0701004);天津市杰出青年科学基金(20JCJQJC00190)。

摘　　要：太赫兹(THz)波由于其诸多独特的性质,有着广泛的应用前景。然而由于相关材料和器件的发展相对滞后,太赫兹技术在实际中的应用尚有诸多限制。超材料和超表面概念的提出,能够对太赫兹波的相位、振幅、偏振进行有效操控,为太赫兹技术的发展提供了许多新的思路。其重要的功能之一是依靠相位不连续将入射波反射到非镜面方向,即通称的广义斯涅尔定律。然而,此前报道的大多数异常反射装置的效率都相对较低,在实际应用中存在局限性。针对这一问题,文中提出了一种太赫兹超表面异常反射器,将法向入射光反射到40°方向且不改变其偏振,并从理论上阐述了提高效率的思路,且通过数值模拟展示其有效性。通过使用全介质材料构建超表面从而消除材料损耗,并利用不同布洛赫波的耦合以提供非局部响应,令器件的工作效率超过99%。此外,这一设计理念可以推广到偏振无关器件中,并且对其他类似的器件也有一定参考意义。这一工作有潜力被应用于太赫兹波激光器、太赫兹波腔谐振器等太赫兹波实际器件中。Terahertz(THz) wave has broad application prospects because of its many unique properties.However, due to the relative lag in the development of related materials and devices, there are still many limitations in the practical application of terahertz technology. Metamaterials and metasurfaces can effectively manipulate the phase, amplitude, and polarization of terahertz waves, providing many new possibilities for the development of terahertz technology. One of its important functions is to reflect incident waves in non-specular directions through phase discontinuities, commonly known as generalized Snell’s law. However, most of the previously reported anomalous reflection devices are relatively inefficient and have limitations in practical applications. To solve this problem, we propose a terahertz metasurface anomalous reflector that reflects normal incident light to a 40° direction without changing its polarization. We theoretically expound the idea of improving efficiency and demonstrate its effectiveness through numerical simulation. We construct a metasurface using alldielectric materials to eliminate material losses and exploiting the coupling of different Bloch waves to provide a non-local response, the operating efficiency of the device can be increased to more than 99%. In addition, our design concept can be generalized to polarization-independent devices and could be useful for other similar devices. This work has the potential to be applied to practical terahertz devices such as terahertz lasers and terahertz cavity resonators.

关 键 词：太赫兹 超表面 异常反射 非局域性 

分 类 号：O436[机械工程—光学工程]